Devices and methods for performing in vivo imaging of passages or cavities within a body are well known in the art. Such devices may include, inter alia, endoscopic imaging systems and devices, for example, an in vivo capsule, for performing imaging in various internal body cavities.
For it to be swallowable, an autonomous in vivo capsule must not exceed a certain girth and length, which in turn may limit the space available for the capsule components including its energy source. The limitation on the size of the energy source may translate into a limitation on the power available for the operation of the capsule.
The passage of an autonomous in vivo capsule through the peristalsis of the gastrointestinal (GI) tract may take several hours. A propelled capsule may complete the passage in a shorter time, but may require more energy to do it. Furthermore, the capsule may travel for several hours during the gastrointestinal tract before it reaches a region of interest, for example, the colon. It is important to ensure that upon reaching the region of interest, the capsule's energy source can provide sufficient energy for the operation of the capsule during the passage through the region of interest and at a desired rate of operation, such as a desired frame capture rate.
While traveling inside the body, the imaging device may capture images of, for example, surfaces of the intestine and may transfer the captured images at a fixed frame rate, continuously, to an image recorder outside the body to be analyzed by a physician. The device may move unevenly inside the passages or cavities of the body. For example, an in vivo capsule passing through a GI tract may be moving “slowly” in some part of the GI tract, and at some point of time and/or position may start to move “rapidly”. If the in vivo device is capturing images at a fixed time interval, a physician performing diagnosis of the patient may receive fewer images for that part of the GI tract as a result of this sudden change in the movement of capsule.
Various methods may be used to control the rate of images being captured by the imaging device and/or transferred to a receiver or recorder. The imaging device may increase or decrease the rate of image capturing and the corresponding rate of frames being sent by the device.
However, when the rate of image capture and transmission is increased, so too is the power consumption. In some cases, variable transmission rates that are too high may deplete the power resources of the device. If the energy resources are depleted before the device is expelled from the body, regions of the GI tract may not be imaged.